The Commerce Department is hiking import duties on solar energy equipment from China and Taiwan, closing a loophole that had allowed Chinese manufacturers to avoid tariffs and sell at illegally low prices in the U.S.

Steep anti-dumping duties will now placed on imports of most solar panels made in China and solar cells from Taiwan, likely raising the cost of solar energy at a time of falling oil prices.

The Commerce Department has imposed preliminary anti-dumping tariffs ranging from 26%-165% on Chinese and Taiwanese solar cell/module imports. The tariffs come on top of the anti-subsidy tariffs imposed in early June, and in spite of a WTO ruling declaring U.S. solar tariffs violate global trade rules.

Among the affected exporters,Trina (NYSE:TSL) is getting off the lightest: Between the June and July tariffs, it's dealing with a combined rate of 29.3%.

Yingli (NYSE:YGE), Canadian Solar (CSIQ), and Hanwha (NASDAQ:HSOL) are set to pay a combined rate of 47.27%, and Suntech (NYSE:STP) a combined rate of 49.24%. ReneSola (NYSE:SOL) and JinkoSolar (NYSE:JKS) have to pay a 58.87% anti-dumping rate.

Chinese module makers can pay 2012 tariff rates instead if they use Chinese (rather than Taiwanese) cells. Those rates are generally a little milder, often ranging from 24%-31%.

"The tariffs in this case are so high as to prohibit basically any manufacturer from selling at a competitive price in to the U.S," says GTM Research's Shayle Kann. A final DOC ruling on the tariffs is expected around Dec. 15, and an ITC ruling on Jan. 29. (the full ruling - .pdf)

U.S. rivals First Solar (NASDAQ:FSLR) and SunPower (NASDAQ:SPWR) stand to benefit. Their shares rose following the June tariff announcement.

The Department of Commerce has imposed new preliminary tariffs on Chinese solar module imports, covering both modules featuring Chinese and non-Chinese cells. Trina (NYSE:TSL) is seeing an 18.56% tariff, bankrupt Suntech (NYSE:STP) a 35.21% tariff, and most other firms a 26.89% tariff.

The move follows a complaint from Germany's SolarWorld that Chinese firms are using a loophole involving imported cells to sidestep the DOCs 2012 tariffs. A separate anti-dumping decision is due on July 25.

Morgan Stanley notes many were expecting either a lower tariff (perhaps around 15%) or a settlement similar to the EU/China deal. Not surprisingly, the Chinese government says it's "strongly dissatisfied" with the DOC's action, and warns it could hurt trade ties.

U.S. peers First Solar (FSLR+2.5%) and SunPower (SPWR+5.5%) are higher. But SolarCity (SCTY-2.8%) and SunEdison (SUNE-3.5%) are off, as investors fear higher panel costs for solar projects. Also: SunEdison has announced a new $500M convertible debt offering. $350M-$400M of the proceeds will go to its TerraForm Power (Pending:TERP) spinoff.

Bankrupt Suntech's (STP) Singapore unit has been ordered by a local court to pay subsidiary PSS (in the midst of liquidation proceedings) $263.9M, along with interest and other costs. PSS' liquidator says further recovery actions will be taken against Suntech.

The WSJ reported ten days ago Suntech is planning a Chap. 15 U.S. bankruptcy filing.

Suntech plans to file for protection under Chapter 15; if recognized by a U.S. judge, the Chinese solar panel maker will receive the benefits of U.S. bankruptcy law, including a halt to lawsuits and the prevention of creditors from seizing assets.

It remains unclear how much money from the reorganized company would eventually flow to the convertible bonds the company defaulted on in March.

Zhou Weiping, bankrupt Suntech's (STP) interim CEO/CFO for the last four months, has resigned from his position, and from the company's board. Zhou says "personal reasons" are responsible for his departure. (PR)

Zhou took over the CEO and CFO roles from David King in September; at the time, Suntech said it would "commence a search for a new CFO." Now, the company says it plans to "announce new management" following a review by its board and joint provisional liquidators.

Solar stocks aren't getting left out on a day that's seeing a number of heavily-shorted names shoot higher (see NQ Mobile and InvenSense). With one trading day left in the year, the Guggenheim Solar ETF (TAN+2.5%) is up 128% YTD.

China Sunergy (CSUN+15.5%) is today's biggest winner: The company announced this morning it has completed the sale of a 5MW U.K. solar project to a local firm.

Trina Solar and Real Goods Solar, each of which announced new solar project deals, are also posting solid gains. As is ReneSola (SOL+3%), which announced it has signed a memorandum of intent to sell 60MW worth of Chinese solar projects.

With a lot of good news having been priced in this year, several Chinese solar stocks are selling off after JA Solar and LDK Solar both provided mixed Q3 numbers and fairly good guidance (I, II). LDK (LDK-2.5%), which continues to deal with major liquidity/debt payment issues (the company just reached a new two-week debt forbearance deal with creditors), has given up its premarket gains.

It's unclear if the liquidators will be able to stop the sale. An officer at the Wuxi Intermediate Court states the deal is "already settled."

Suntech shares initially dove on the pink sheets in response to the news, but are now close to breakeven. They rallied yesterday, but are still down sharply from where they traded before the company announced on Nov. 6 it had filed for a "provisional liquidation" in the Cayman Islands.

Trading in Suntech's (STP) shares will be suspended before Monday's open. The NYSE cites uncertainty regarding the troubled solar module vendor's ability to complete its Form 20-F in time, given its restructuring and financial restatement efforts. (PR)

Suntech (STP-16.7%) has filed for a "provisional liquidation" in the Cayman Islands, where the company is incorporated. The company argues the move will give it more time to conclude negotiations with stakeholders and finish its restructuring.

Suntech also says it'll "consider pursuing" a U.S. Chapter 15 bankruptcy filing (used for filings from non-U.S. companies) once the Cayman Islands approves its application to obtain similar protections in the U.S.

The announcement comes shortly after Suntech struck a deal with Shunfeng Photovoltaic to sell its bankrupt Wuxi, China unit for $492M. Some of the company's disgruntled U.S. bondholders have petitioned an NY court to force Suntech into involuntary bankruptcy.